JPH1048603A - Variable information display window - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily change the information displayed in a window by using characteristics of a smectic liquid crystal so that writing information by either heat or an electric field and erasing information by the other can be repeated. SOLUTION: A transparent electrode 12 and a liquid crystal/polymer composite film (PDLC film) 13 having dispersion of a smectic liquid crystal in a polymer matrix are formed on the surface of a base film 11 such as a polyester film. Further, a transparent electrode 14 may be formed on the surface of the PDLC film 13 or a protective layer 15 may be directly formed. This PDLC film 13 is adhered to the inner surface of a plate glass 16 to obtain a variable information display film. Or, instead of the base film such as a polyester film, a plate glass 16 or transparent plastic plate (org. glass) can be used. In the obtd. PDLC film, information can be written by either heat or an electric field and information can be erased by the other, and these processes can be repeated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable information display window capable of repeatedly displaying various information on windows in other places such as houses, office buildings, factories, trains, and buses.

[0002]

2. Description of the Related Art Conventionally, various types of information have been added to the above-mentioned various windows for the purpose of advertising and information transmission. As a method of adding the company name and other advertising information to the window as described above, a method of printing and printing with a printing ink for glass, a method of printing on the window glass, a method of printing on the inside of the window glass at the time of manufacturing the window glass A method of attaching a film or paper, a method of cutting out a colored plastic film, and attaching this to a window glass have been used.

[0003]

In the above-mentioned conventional method, the method of printing on window glass is suitable for displaying a certain amount of information for a long period of time. It is difficult to erase existing information and print new information. Also, the method of displaying various kinds of information by sticking inside the window glass after forming the window is complicated when replacing information, and a large amount of used printed matter is generated. Although incineration and regeneration processing are performed, in any case, it is a great waste of resources and energy, which is not preferable in terms of environmental conservation. Accordingly, an object of the present invention is to provide a variable information display window capable of repeatedly displaying necessary information without the above-mentioned complexity and waste of resources.

[0004]

The above object is achieved by the present invention described below. That is, the present invention comprises a transparent body having a liquid crystal / polymer composite film (hereinafter, simply referred to as a PDLC film) in which a smectic liquid crystal is dispersed in a polymer matrix, and the film is formed of one of heat and an electric field. A variable information display window characterized in that writing of information and erasing of information on the other side are configured to be repeatable.

According to the variable information display window of the present invention, it is possible to repeatedly write information in one of heat and electric field and delete information in the other, due to the characteristics of the smectic liquid crystal. It is very easy to change the contents, and no waste such as paper or plastic film is generated.

[0006]

Next, the present invention will be described in more detail with reference to preferred embodiments. FIG. 1a is a diagram schematically illustrating a cross section of an example of the variable information display window of the present invention. In the figure, reference numeral 11 denotes a base film such as a polyester film, and the surface of the base film
A DLC film 13 is formed. The transparent electrode 14 may be formed on the surface of the PDLC film, but the protective layer 15 may be formed directly on the surface of the film 13 without providing the transparent electrode 14. The details of each layer will be described later. Such a PDL
The variable information display film of the present invention can be obtained by adhering the C film to the inner surface of the window glass 16 by an appropriate method. FIG. 1B is a view similar to FIG. 1A except that a glass plate 16 or a transparent plastic plate (organic glass) is used instead of the base film such as the polyester film.
This is an example in which each layer such as a DLC film is formed. PD as above
The LC film can write information in one of heat and electric field and erase information in the other, and this writing and erasing can be repeated.

As for writing and erasing of information in the variable information display window of the present invention as described above, for example, FIG.
In a and b, the PDLC layer is heated to a predetermined temperature as required, and in this state, the surface of the protective layer 15 is charged by a corona discharger or the like, and a predetermined voltage is applied between the protective layer and the electrode 12. Then, the liquid crystal in the PDLC layer is oriented, and PD
The LC layer becomes a transparent state, and the transparent state is maintained by cooling and charge removal. In this state, the PDLC layer is heated in an image-like manner by a thermal head, a hot pen, or the like, whereby the alignment state of the liquid crystal of the PDLC layer is eliminated, and the portion where heat is applied becomes a light scattering state, and information is recorded.
The recorded information is not erased unless the PDLC layer is reheated.

In the case of FIG. 1A, the above-described writing is performed in a state where the electrodes, PDLC layer, protective layer, etc. are formed on the base film 11, and the writing is affixed to the glass plate 16 of the window. Erase and write, and then re-attach. In both FIGS. 1a and 1b, information can be rewritten by forming a window and then moving a writing device and an erasing device such as a thermal head and a corona charger on the surface. The information to be written can be improved in contrast ratio by using a dichroic dye, and the liquid crystal layer is formed of a YMC matrix by using a liquid crystal to which a dichroic dye of three primary colors of yellow, magenta and cyan is added. Thus, various color displays and full-color image displays are also possible.

Writing (recording) of visible information on the PDLC film
The principle of / erasing uses light transmission and light scattering in an alignment state and a random alignment state of liquid crystal molecules by heat and an electric field (heat-electric field mode). Therefore, the recorded information is displayed as white turbid light due to light scattering (when dichroic dye is used, colored light due to the dye), and when erasing is performed by transparency through light transmission, printing (writing) is performed. ) Is performed by a heating means, such as a thermal head, which can be heated in a spot manner.
This can be performed by applying an electric field to the DLC film that is equal to or more than the threshold value of the liquid crystal alignment.

In the PDLC film, the liquid crystal is μs by applying an electric field.
ec. Because it is oriented in the order, high-speed rewriting process can be performed compared to various reversible display devices in the conventional heat-heat mode,
It is suitable as a PDLC film used for the variable information display window of the present invention. The number of rewrites is sufficient, and the visibility of the displayed image is improved by using a dichroic dye in combination, the memory is excellent in a natural environment, and the displayed image is not unintentionally erased.

The liquid crystal material used in the present invention is a smectic liquid crystal, and any conventionally known smectic liquid crystal can be used. It is preferable that these smectic liquid crystals have a wide temperature range exhibiting a nematic phase. In the present invention, by using a smectic liquid crystal material having a temperature range exhibiting a nematic phase of 1 ° C. or more, P is reduced.
The driving voltage when the DLC film is made transparent can be reduced. A dichroic dye may be mixed in the smectic liquid crystal at a ratio of, for example, 1 to 10 parts by weight per 100 parts by weight of the smectic liquid crystal for the purpose of improving the contrast ratio, coloring, and the like. In that case, the dichroic dye contained in the liquid crystal is not particularly limited,
Any of azo, perylene, anthraquinone, etc. can be used, and a dichroic dye suitable for the color tone required for display on the variable information display window is used in combination with a liquid crystal, a matrix material, a capsule wall material, etc. Can be

A polymer material forming a polymer matrix for dispersing the liquid crystal or liquid crystal containing a dichroic dye (hereinafter simply referred to as liquid crystal) is not compatible with liquid crystal, and is excellent in transparency and film-forming ability. Any polymer material can be used. Specifically, an appropriate polymer material, for example, a polyvinyl alcohol resin, a fumarate-based resin, an epoxy resin, a polycarbonate resin, a UV-curable resin of polythiol, or the like is used according to the method of forming the PDLC film.

Further, the liquid crystal may be microencapsulated, and the microencapsulation method is not particularly limited, and a conventionally known method is used. For example, a liquid crystal or a liquid crystal in which a radical-reactive monomer is dissolved in an aqueous medium is mixed with a radical-reactive surfactant, a water-soluble protective colloid, or a radical-reactive protective colloid, or a mixture of two or more of these. By emulsifying and dispersing, dissolving or dispersing the radical initiator in water or liquid crystal, and raising the temperature to the decomposition temperature of the initiator, a capsule wall film surrounding the liquid crystal particles can be produced. As the radical polymerizable monomer to be dissolved in the liquid crystal, one having compatibility with the liquid crystal, such as styrene, vinyl acetate, and (meth) acrylate, can be used. Preferably, a mixture of two or more functional monomers is preferred. As the radical initiator, a water-soluble, oil-soluble or redox-based initiator can be used. It is also possible to initiate polymerization using ionizing radiation such as gamma rays or electron beams.

In the microencapsulated liquid crystal having the above structure, the polymer material used as the wall material is preferably used in a range of 5 to 25 parts by weight per 100 parts by weight of the smectic liquid crystal as the core material. If the amount of the wall material used is less than the above range, problems such as oozing of liquid crystal cannot be sufficiently solved because the wall is thin. On the other hand, if the amount used exceeds the above range, the thickness of the wall is large, so that when the dichroic dye is used, the amount of the dichroic dye incorporated into the wall increases, and the wall is colored. This is not preferable because the reflection density at the time of application does not become sufficiently low. The thickness of the wall in the encapsulated state varies depending on the liquid crystal material, polymer material, encapsulation method, and the like used, but is generally about 10 to 100 nm.

As a method of dispersing the liquid crystal in the polymer matrix, any of conventionally known methods such as a phase separation method and an emulsion method can be used. The emulsion method will be briefly described below as a typical example. However, the present invention is not limited to the emulsion method. In the emulsion method, the liquid crystal is emulsified and dispersed in a medium mainly composed of water containing a surfactant or a protective colloid as necessary, and polyvinyl alcohol, gelatin, an acrylic acid copolymer, a water-soluble alkyd resin A method of applying a water-soluble or water-dispersible polymer material such as, for example, on a suitable substrate and drying to form a film having a suitable thickness. PDLC with liquid crystal uniformly dispersed in it
A film is formed.

As a method of emulsifying and dispersing the liquid crystal in an aqueous solution or aqueous dispersion of the molecular matrix, a mixing method using various stirring devices such as an ultrasonic dispersion method and a mechanical dispersion method, and a film emulsification method [Tadao Nakajima, Masataka Shimizu, PHARMTEC
H JAPAN Vol. 4, No. 10, No. (1988)] is effective. The particle size of the obtained liquid crystal emulsion particles has a diameter of 1 in the volume distribution so that the liquid crystal molecules are easily oriented in the matrix or the capsule.
It is desirable that the proportion of the liquid crystal particles having a size of μm or less be 10% or less in all the particles. For example, when an O / W emulsion of a liquid crystal is obtained by a porous glass (MPG) film emulsification system, the volume distribution of the liquid crystal to be emulsified and dispersed is adjusted by setting the average pore diameter of the MPG to be used to 0.3 μm (diameter) or more. Can be in the above range. Also, using a mechanical dispersion method, for example, the condition of the mechanical dispersion is set to a rotational speed of 1,000 r.
By setting the pm and the time to 1 minute or more, a liquid crystal emulsion containing liquid crystal particles having a volume distribution within the above range can be obtained.

Using the liquid crystal dispersion thus obtained, PD
As a method of forming an LC film, a method of applying and drying the liquid crystal dispersion on a substrate is preferable. Examples of the coating method include an electrodeposition method, a screen coating, a blade coating, a knife coating, a slide coating, an intrusion coating, and a fountain coating. The P obtained in this way
The thickness of the DLC film is preferably about 3 to 23 μm. If the film thickness is too small, light scattering (turbidity) at the time of heating becomes insufficient, and if the film thickness is too large, a large driving voltage is required for the alignment of the liquid crystal.

The amount of liquid crystal used is usually such that the mixing ratio (weight ratio) of the polymer matrix forming material / liquid crystal is 65/3.
The range of 5-35 / 65 is desirable. If the amount of liquid crystal used is too small, not only is the transparency of light when a voltage is applied insufficient, but it is also insufficient in that a large voltage is required to make the film transparent. If the amount of the liquid crystal used is too large, not only is light scattering (turbidity) at the time of heating insufficient, but also the strength of the film is undesirably reduced.

As described above, the variable information display window of the present invention
It is composed of at least a PDLC film and an electrode for applying an electric field to the film. This electrode may sandwich both surfaces of the PDLC film, or may be provided only on the back surface. The application of the voltage when the electrode is provided only on the back surface is performed by, for example, corona discharge. When writing information using a thermal head or the like, it is preferable to form a protective layer on the surface of the PDLC film in order to protect the PDLC film.

The conductive substrate on which the PDLC film is formed by coating is a substrate generally used for a conventionally known liquid crystal display device. For example, a transparent conductive substrate such as ITO, SnO ₂ , and ZnO is used. An electrode substrate in which a material is attached to a transparent substrate such as a polymer film such as PET (polyethylene terephthalate) or glass or glass. When a PDLC film formed on a transparent conductive substrate is sandwiched between the conductive substrate and the conductive substrate, the conductive substrate is generally used for a conventionally known liquid crystal display element. For example, ITO, SnO An electrode substrate is used in which a transparent conductive material such as a _2- based or ZnO-based material is adhered to a transparent substrate such as a polymer film such as PET.

When a protective layer is formed on the surface of a PDLC film formed on a transparent conductive substrate, the polymer material forming the protective layer has excellent adhesion to the PDLC film and forms a transparent film. Whose refractive index is PDL
Any polymer material can be used as long as the difference is 0.05 or less as compared with the refractive index of the matrix forming polymer material of the C film. For example, when polyvinyl alcohol is used as the matrix-forming polymer material, preferred protective layer-forming polymer materials include trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and pentaerythritol tetra A crosslinked polymer composed of a polyfunctional monomer such as (meth) acrylate is exemplified. These monomers can be used alone or as a mixture of two or more kinds, and further mixed with other monomers.

It is desirable that the protective layer formed on the surface of the PDLC film has a smooth surface and that the difference between the refractive index of the protective layer and the refractive index of the polymer matrix is 0.05 or less. If the difference exceeds 0.05, the difference between the refractive index of the liquid crystal and the refractive index of the protective layer when a voltage is applied increases,
Light scattering is increased and the contrast is reduced. More preferably, it is 0.03 or less. Further, the average roughness (Ra) of the obtained protective layer is preferably less than 0.1 μm. If the average roughness is 0.1 μm or more, light is scattered on the surface of the protective layer, and the contrast is reduced.

As a method for forming the protective layer, for example, PD
PDL as a solution in which the polymer material for forming the protective layer is dissolved in a solvent that does not dissolve the LC film, or as an emulsion of an appropriate medium
After applying the above-mentioned monomer which forms a film by polymerization in the same manner as the formation of the C film onto the PDLC film surface, the monomer is converted into a polymer by an appropriate means (heating, electron beam irradiation, etc.). A protective layer or a monomer layer is separately formed on the release sheet surface by the above method, and the protective layer or the monomer layer is transferred and laminated on the PDLC film surface (in the case of a monomer layer, Polymerization and curing at the time of transfer or after transfer). The thickness of the formed protective layer is preferably in the range of 1 to 5 μm.

FIG. 2 is a schematic view showing another example of the variable information display window of the present invention. The PDLC film 22 shown in FIG.
This is an example in which various kinds of information are displayed on the film 22 and are adhered to the window glass. In the figure, reference numeral 20 denotes a window glass, and reference numeral 21 denotes a flexible PDLC film take-up device (which may also serve as an upper window frame). The PDLC film 22 is wound around the take-up device 21 and freely. It can be withdrawn. Below the winding device 21, an erasing unit 24 incorporating a heating device and a corona charger and a writing unit 23 having a thermal head such as a small printer are provided. Now, it is assumed that information of a predetermined state is recorded on the PDLC film. When changing the content of the information, the erase unit 24 is operated to activate the PDLC film 22.
And the displayed information is erased. Next, by pulling out the PDLC film 22 at a predetermined speed while operating the writing unit 23, the PDLC film 22 on which other information is displayed is lowered and adheres to the window glass 20. The above operation can be repeated semi-permanently.

FIG. 3 is a schematic view showing another example of the variable information display window according to the present invention, in which the left and right frames (not shown) of the window are PDL.
The configuration is such that the winding portions 31 and 31 ′ of the C film 32 may also be used. In this example, a writing unit 33 is provided near the entrance of one of the winding units 31 and an erasing unit 34 is provided near the entrance of the other winding unit 31 '. For example, the writing unit 33 is provided near the entrance of the winding unit 31 or 31'. May be provided with both a writing unit 33 and an erasing unit 34. As described above, the mounting positions of the units 33 and 34 are not particularly limited.

In FIG. 3, in order to write information on the PDLC film 32, the winding unit 31 or 31 'is a roller (not shown).
Is rotated by a drive motor (not shown), and the PDLC film 32 is rotated.
Is wound around the winding unit 31. If information has already been written on the PDLC film 32, the winding is performed while erasing the written information by operating the erasing unit. In order to newly write information, printing is performed on the right half of the PDLC film 32 by synchronizing the rotation of the rollers (not shown) of the winding units 31 and 31 ′ with the operation of the writing unit. Next, the rotation of the rollers (not shown) of the winding units 31 and 31 ′ is synchronized with the operation of the writing unit 33 to print on the left half of the PDLC film 32. The writing unit 33 is provided with, for example, a thermal head, and desired information is recorded and displayed on the PDLC film 32 by heating.
FIG. 4 shows a schematic configuration diagram of an example of a writing unit and an erasing unit when writing and erasing on the PDLC film constituting the variable information display window. In FIG. 4, the writing unit 4
3 and the erasing unit 44 are shown integrally, which means that they can be separated into units indicated by broken lines.

The writing unit 43 is provided with a thermal head 46 facing the platen roller 45.
The thermal head 45 receives a predetermined signal and receives the PDLC film 4.
2 is written with desired information. The erasing unit 44
A power supply 48 for supplying a predetermined voltage to the charger 47 and a platen roller 45 for reliably bringing the processing surface into contact with the ground roller 49 are disposed opposite to the ground roller 49. PDLC
The recording information is erased by applying a voltage while heating the film 42 as necessary, and the information is recorded by heating by the thermal head 46. The charger 47 is a corona charger having a tungsten wire connected to a power supply 48 inside. In addition, the ground roller 49 and the power supply 42 are grounded, and a potential difference is generated between the surface of the PDLC film 42 charged by the charger 47 and the contact surface with the ground roller 49, thereby causing an electric field in the vertical direction of the PDLC film 42. Is applied.

As the charger 47, a conventionally known corotron charger, scorotron charger and the like can be used. As the ground roller 49, a plastic or rubber roller or the like containing a conductive material such as metal or conductive carbon black can be used. Particularly preferred is a roller made of an elastic material such as rubber. Both the electric field applying means 47 (charging device) and the thermal head 46 can be used for writing and erasing information. However, by using the electric field applying means for erasing, the display is not erased at a temperature under a natural environment, and the display reliability is reduced. This makes it possible to provide an excellent display.

The electric field applying means of the erasing unit 44 is not limited to the above-mentioned method.
Any of electric field applying means such as a charging method described in JP-A No. 03249 and Japanese Patent Application No. 6-302701 and an electrode method described in Japanese Patent Application No. 6-30270 can be used. As the writing unit 43, a thermal head used for a thermal printer is used. A heating means using a laser can be used instead of the thermal head.

[0030]

Next, the present invention will be described more specifically with reference to examples. Example 1 Smectic liquid crystal: SCE-9 (manufactured by Merck Limited, temperature range showing a nematic phase: 91.0 to 11)
(5.0 ° C.), 100 parts of dichroic dye: S-428 (black color / transparent dichroism) (manufactured by Mitsui Toatsu Chemicals) was added, and the mixture was stirred at 120 ° C. for 30 minutes. To this mixed solution, polyvinyl alcohol: EG-05 (manufactured by Nippon Synthetic Chemical Industry,
(Polymerization degree: 500, saponification degree: 86.5 to 89.0) 252.8 parts of a 5% by weight aqueous solution was added, and a porous glass membrane tube (manufactured by Ise Chemical Industry) having a pore diameter of 1.10 μm (diameter) was used. It was dispersed by a membrane emulsification method.

The particle size distribution of the liquid crystal was measured using Microtrack MK.
-IISPA particle size distribution analyzer (LEED & NORTHRUUP
As a result, the average particle diameter (diameter) in the volume distribution was 7.7 μm, and the ratio of particles having a diameter of 1 μm or less was 1.5%. PVA: KH-20 (manufactured by Nippon Synthetic Chemical Industry, degree of polymerization: 2,000, degree of saponification: 78.5 to 81.5) was added to this dispersion as a thickener,
CE-9 / (KP-06 + KH-20) = 50/50
(W / w) and stirred. Using this dispersion, I-deposited ITO deposited white PET film (Toray)
It was applied on the TO surface using a doctor blade and dried to form a film. The thickness of the obtained PDLC film was 10.3.
μm. The refractive index of polyvinyl alcohol (EG-05 and KH-20) forming the matrix of the PDLC film was 1.51. To measure the refractive index, use a refractometer:
The measurement was performed using DVA-36L (manufactured by Mizojiri Optical Industry).

Trimethylolpropane triacrylate: EXG-40-8 (manufactured by Dainichi Seika) was applied to a PET release film: MC-19 (manufactured by Reiko) using a doctor blade and dried. A film was formed to a thickness of 8 μm. After laminating the film surface with the PDLC film surface facing each other, irradiating it with 4 Mrad electron beam to polymerize and dry the acrylate, and then peeling off the release film, the film was smooth (average roughness: Ra). = 0.01 μm). The refractive index of the cured polymer film of trimethylolpropane triacrylate having the same film thickness was 1.50 (the refractive index was measured using the refractometer described above).

The thus obtained PDLC film was cut into the same size as the glass window, and bonded to the inside of a house window glass to obtain a variable information display window of the present invention. PD above
For writing information on the LC film, a thermal head used as a writing unit in a thermal printer (head resolution: 6 dots / mm, heating amount 0.8 mJ / dot)
Was used. A corona charger was used as the erasing unit. Connect the thermal head to the microcomputer,
As a result of outputting the character information input to the microcomputer to the PDLC film, clear black characters were displayed. This PDLC film was adhered to a window glass. Next, the PDLC film is peeled from the window glass, and the entire surface is about 75 to 9
When an electric field was applied by a corona charger while heating to 5 ° C., all surfaces became transparent and the displayed image was completely erased. This erased PDLC film could be written and erased any number of times.

Example 2 The PDLC film obtained in Example 1 was incorporated in a winding device shown in FIG. 2 and attached to an upper frame of a window glass of an office building to constitute a variable information display window of the present invention. For writing information of the PDLC film in the variable information display window, a thermal head (head resolution: 6 dots / mm, heating amount 0.8 m) used for a thermal printer as a writing unit
J / dot). A corona charger was used as the erasing unit. A thermal head was connected to the microcomputer, and the character information input to the microcomputer was output to the PDLC film. As a result, clear black characters were displayed. Next, the entire surface of the PDLC film is made about 75 to 9
When an electric field was applied by a corona charger while heating to 5 ° C., all surfaces became transparent and the displayed image was completely erased. This erased PDLC film could be written and erased any number of times.

Example 3 The PDLC film obtained in Example 1 was incorporated in a wrap-around display device shown in FIG. 3, and fixed to left and right window frames to form a variable information display window of the present invention. As a writing unit, a thermal head (head resolution: 6 dots / mm, heating amount: 0.8 mJ / dot) used in a thermal printer was used. A corona charger was used as the erasing unit. A thermal head is connected to the microcomputer, and the character information input to the microcomputer is transferred to the PD.
As a result of outputting to the LC film, clear black characters were displayed. Next, when an electric field was applied by a corona charger while heating the entire surface of the PDLC film at about 75 to 95 ° C., all surfaces became transparent and the displayed image was completely erased. This erased PDLC film could be written and erased any number of times.

[0036]

According to the present invention, as described above, it is possible to repeatedly write information in one of heat and electric field and erase information in the other, due to the characteristics of the smectic liquid crystal. It is very easy to change the content of the information, and no waste such as paper or plastic film is generated.

[0038]

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a variable information display window of the present invention.

FIG. 2 is a schematic diagram showing an example of a variable information display window of the present invention.

FIG. 3 is a schematic diagram showing an example of a variable information display window of the present invention.

FIG. 4 is a writing unit for displaying and erasing information;
FIG. 3 is a schematic diagram illustrating an example of an erasing unit.

[Explanation of symbols]

 11: Base film 12: Electrode 14: Transparent electrode 15: Protective layer 16, 20: Window glass 21: Winding device 13, 22, 32, 42: PDLC film 23, 33, 43: Writing unit 24, 34, 44 : Erase unit 31, 31 ': Winding unit 45: Platen roller 46: Thermal head 47: Charger 48: Power supply 49: Ground roller

Claims (3)

[Claims] 1. A transparent body having a liquid crystal / polymer composite film in which a smectic liquid crystal is dispersed in a polymer matrix, wherein the film writes information in one of heat and an electric field and writes information in the other. A variable information display window, which is configured to be able to be deleted repeatedly. 2. The variable information display window according to claim 1, wherein the liquid crystal is microencapsulated. 3. The variable information display window according to claim 1, wherein the variable information display window is incorporated in a writing and erasing unit.